One of my coaches said this to me during a training camp. He said that when Cortez invaded, he was hearing doubts from his men that they would be successful. So he set fire to all of their ships, eliminating their way home. This way the men had to push forward, had to be victorious. there was no other option.

So when you're facing a big challenge, eliminate plan B. Only give yourself the option of success.

(Sorry if this seems convoluted, as I read it back to myself I realize that he made it sound way more inspiring)